Methods of Operating a Pulse Width Modulation Valve, and Related Agricultural Machines and Monitoring Systems

Abstract

An agricultural machine includes a chassis, a product tank containing a fluid, and a fluid distribution system in fluid communication with the product tank. The fluid distribution system includes at least one fluid outlet line configured to deliver a fluid to an agricultural field, at least one pulse width modulation valve in fluid communication with the at least one fluid outlet line, and at least one pressure sensor upstream of the at least one pulse width modulation valve, the at least one pressure sensor configured to measure a fluid pressure proximate the at least one pulse width modulation valve. The agricultural machine further includes a monitoring system configured to determine at least one of a duty cycle or a modulation frequency of the at least one pulse width modulation valve based on the fluid pressure. Related methods and monitoring systems are also disclosed.

What is claimed is: 
     
         1 . An agricultural machine, comprising:
 a chassis;   a product tank containing a fluid;   a fluid distribution system in fluid communication with the product tank, the fluid distribution system comprising:
 at least one fluid outlet line configured to deliver a fluid to an agricultural field; 
 at least one pulse width modulation valve in fluid communication with the at least one fluid outlet line; and 
 at least one pressure sensor upstream of the at least one pulse width modulation valve, the at least one pressure sensor configured to measure a fluid pressure proximate the at least one pulse width modulation valve; and 
   a monitoring system configured to determine at least one of a duty cycle or a modulation frequency of the at least one pulse width modulation valve based on the fluid pressure.   
     
     
         2 . The agricultural machine of  claim 1 , wherein the agricultural machine comprises a crop sprayer. 
     
     
         3 . The agricultural machine of  claim 1 , further comprising a boom comprising at least one boom arm configured to laterally extend from the chassis, wherein the at least one fluid outlet line is operably coupled to the at least one boom arm. 
     
     
         4 . The agricultural machine of  claim 3 , wherein:
 the at least one pulse width modulation valve comprises a plurality of pulse width modulation valves; and   the at least one boom arm comprises a plurality of sprayer nozzle assemblies, each sprayer nozzle assembly operably coupled to one of the pulse width modulation valves of the plurality of pulse width modulation valves.   
     
     
         5 . The agricultural machine of  claim 4 , wherein each sprayer nozzle assembly comprises a flow sensor. 
     
     
         6 . The agricultural machine of  claim 5 , wherein the flow sensor comprises an optical sensor configured to measure a frequency about which a projectile rotates within a housing of the sprayer nozzle assembly. 
     
     
         7 . The agricultural machine of  claim 1 , wherein the agricultural machine comprises an agricultural implement comprising row units, wherein at least one of the row units is in fluid communication with the fluid distribution system. 
     
     
         8 . The agricultural machine of  claim 7 , wherein the at least one row unit comprises a conduit in fluid communication with the fluid distribution system and the at least one pulse width modulation valve. 
     
     
         9 . The agricultural machine of  claim 8 , further comprising a flow sensor in fluid communication with the at least one pulse width modulation valve and the conduit and configured to measure a flowrate of fluid through the at least one pulse width modulation valve. 
     
     
         10 . The agricultural machine of  claim 1 , wherein the monitoring system is configured to determine a flowrate of the fluid flowing through the at least one pulse width modulation valve based on a measured flowrate and the at least one of the duty cycle or the modulation frequency of the at least one pulse width modulation valve. 
     
     
         11 . The agricultural machine of  claim 1 , wherein the chassis is supported by ground-engaging elements. 
     
     
         12 . The agricultural machine of  claim 1 , wherein the at least one pressure sensor is within a sensor assembly directly coupled to the at least one pulse width modulation valve. 
     
     
         13 . The agricultural machine of  claim 1 , further comprising at least one of:
 an accelerometer configured to measure an acceleration of the at least one pulse width modulation valve; or   a magnetometer configured to measure at least one magnetic property caused by actuation of the at least one pulse width modulation valve.   
     
     
         14 . The agricultural machine of  claim 13 , wherein the monitoring system is configured to determine the at least one of the duty cycle or the modulation frequency of the at least one pulse width modulation valve based on at least one of the acceleration of the at least one pulse width modulation valve or the at least one magnetic property. 
     
     
         15 . The agricultural machine of  claim 14 , wherein the monitoring system is configured to compare the at least one of the duty cycle or the modulation frequency based on the fluid pressure to the at least one of the duty cycle or the modulation frequency based the at least one of the acceleration of the at least one pulse width modulation valve or the at least one magnetic property. 
     
     
         16 . The agricultural machine of  claim 1 , wherein:
 the at least one fluid outlet line comprises a plurality of fluid outlet lines; and   the at least one pulse width modulation valve comprises a plurality of pulse width modulation valves, each fluid outlet line individually in fluid communication with one of the pulse width modulation valves.   
     
     
         17 . The agricultural machine of  claim 16 , wherein the at least one pressure sensor comprises a plurality of pressure sensors, each pressure sensor operably coupled to and upstream of a pulse width modulation valve of the plurality of pulse width modulation valves. 
     
     
         18 . A method of operating a pulse width modulation valve, the method comprising:
 measuring pressure data indicative of a fluid pressure with a pressure sensor upstream of a pulse width modulation valve, the pulse width modulation valve in fluid communication with a fluid distribution line; and   based on the measured pressure data, determining at least one of a duty cycle or a modulation frequency of the pulse width modulation valve.   
     
     
         19 . The method of  claim 18 , wherein measuring pressure data comprises measuring the fluid pressure within a sensor housing directly coupled to the pulse width modulation valve. 
     
     
         20 . The method of  claim 18 , wherein measuring pressure data comprises measuring the fluid pressure with a pressure sensor between the pulse width modulation valve and an inlet of a sensor housing in fluid communication with the fluid distribution line. 
     
     
         21 . The method of any one of  claim 18 , further comprising measuring a flowrate of the fluid to determine a measured flowrate. 
     
     
         22 . The method of  claim 21 , further comprising determining a corrected flowrate based on the measured flowrate and the at least one of the duty cycle or the modulation frequency of the pulse width modulation valve. 
     
     
         23 . The method of  claim 18 , further comprising measuring at least one of vibrations of the pulse width modulation valve or at least one magnetic property caused by actuation of the pulse width modulation valve. 
     
     
         24 . The method of  claim 23 , further comprising comparing the at least one of the duty cycle or the modulation frequency determined based on the fluid pressure to at least one of a duty cycle or a modulation frequency determined based on at least one of the vibrations or the at least one magnetic property. 
     
     
         25 . The method of  claim 18 , further comprising:
 measuring, with a pressure sensor, a fluid pressure within each of a plurality of sensor assemblies each located upstream of a respective pulse width modulation valve; and   based on the fluid pressure of each of the sensor assemblies, determining at least one of a duty cycle or a modulation frequency of the respective pulse width modulation valves.   
     
     
         26 . The method of  claim 18 , wherein determining at least one of a duty cycle or a modulation frequency of the pulse width modulation valve comprises determining the at least one of a duty cycle or the modulation frequency of the pulse width modulation valve using pattern recognition. 
     
     
         27 . A monitoring system for an agricultural machine, the monitoring system comprising:
 at least one processor; and   at least one non-transitory computer-readable storage medium storing instructions thereon that, when executed by the at least one processor, cause the monitoring system to:
 receive, from a pressure sensor, a fluid pressure within a sensor housing upstream of a pulse width modulation valve of a fluid distribution system of the agricultural machine; and 
 based on the fluid pressure, determine at least one of a duty cycle or a modulation frequency of the pulse width modulation valve. 
   
     
     
         28 . The monitoring system of  claim 27 , wherein the instructions cause the monitoring system to measure a flowrate of fluid through the pulse width modulation valve. 
     
     
         29 . The monitoring system of  claim 28 , wherein the instructions cause the monitoring system to compensate the measured flowrate based on the at least one of the duty cycle or the modulation frequency of the pulse width modulation valve.